JP2015184738A - power communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power communication device in which a current consumption is reduced.SOLUTION: A master device 10 is provided with a master device current detection unit 12 that detects total current consumed by a plurality of sensors 20, 30, 40. The plurality of sensors are provided with sensor current detection units 23, 33, 43 and sensor controllers 26, 36, 46 in addition to physical quantity detection units, 21, 31, 41 respectively: the sensor current detection units 23, 33, 43 detecting the current flowing between an input side, which is the side of the master device 10, and an output side, which is the side opposite to the input side; and the sensor controllers 26, 36, 46 determining, on the basis of the current detected by the sensor current detection units, whether to shift to a normal mode which consumes normal current, or to shift to a response mode which shifts to a sleep mode, the current consumption of which is smaller than that of the normal mode, after outputting a response signal based on the detection result detected by the physical quantity detection units. The sensor controllers shift to the response mode when the current detected by the current detection units is less than a first threshold value, and the mode at the time of determination is the normal mode.

Description

  The present invention relates to a power communication device in which a plurality of sensor units are daisy chain connected to a master device.

  Conventionally, a power communication device has been proposed in which a plurality of sensor units are connected in a daisy chain to an ECU (Engine Control Unit) of a vehicle as a master device (see, for example, Patent Document 1).

  Specifically, in this power device, the plurality of sensor units have the same configuration, and include an acceleration detection unit. And if the detection result detected by the acceleration detection part of each sensor part is input, ECU will perform various processes according to the said detection result.

JP 2010-137840 A

  However, in the power communication device, when the ECU performs various processes according to the detection result, each sensor unit is always in a normal mode in which a normal current is consumed. For this reason, if the current Icc is consumed in each sensor unit, the current Icc × the number of sensor units is always consumed. Therefore, in recent years, in a power communication device in which a plurality of sensor units are daisy chain connected to such a master device, a power communication device that can reduce current consumption is desired.

  In view of the above points, an object of the present invention is to provide a power communication device capable of reducing current consumption.

  In order to achieve the above object, the invention according to claim 1 includes a master device (10) that performs a predetermined process based on a physical quantity, and a physical quantity detection unit (21 to 41) that detects a physical quantity, A power communication device including a plurality of sensor units (20 to 40) connected in a daisy chain to each other is characterized by the following points.

  That is, the master device (10) has a master device current detection unit (12) that detects the total current consumed by the plurality of sensor units, and each of the plurality of sensor units has the same configuration, together with the physical quantity detection unit. A sensor unit current detector (23-43) for detecting a current flowing between the input side which is the master device side and the output side opposite to the input side, and a normal mode or physical quantity which consumes a normal current A sensor control unit (26 to 46) that determines which of the response modes to shift to the sleep mode that consumes less current than the normal mode after outputting the response signal based on the detection result detected by the detection unit. Each sensor unit control unit in the plurality of sensor units responds when the current detected by the current detection unit is less than the first threshold and the mode at the time of determination is the normal mode. When the current flowing through the master device current detection unit falls below a predetermined threshold due to the plurality of sensor units entering the sleep mode, the master device outputs a plurality of sensors by outputting a wake-up signal. It is characterized by shifting the part to the normal mode.

  According to this, since the transition to the sleep mode with less current consumption is performed after the response signal is output, the current consumption can be reduced.

  In this case, as in the second aspect of the invention, the first threshold value can be made equal to the current consumed by one of the sensor units. According to this, since the plurality of sensor units shift to the response mode sequentially from the last sensor unit, the master device can determine which sensor unit the response signal is output from.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is a block diagram of the electric power communication apparatus in 1st Embodiment of this invention. It is a block diagram which shows the circuit structure of a 1st sensor part. It is a block diagram which shows the circuit structure of ECU. It is a timing chart of an electric power communication apparatus. It is a figure which shows the state of the electric power communication apparatus in the time T0 in FIG. It is a figure which shows the state of the power communication apparatus in the time T3 in FIG. It is a figure which shows the state of the electric power communication apparatus in the time T7 in FIG. It is a figure which shows the state of the electric power communication apparatus in the time T10 in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be described with the same reference numerals.

(First embodiment)
A first embodiment of the present invention will be described. Note that the power communication device of the present embodiment is preferably mounted on a vehicle and used as a component of an occupant protection device such as an airbag.

  As shown in FIG. 1, the power communication device includes an ECU 10 and first to third sensor units 20 to 40 that are daisy chain connected to the ECU 10 by a wire harness or the like. In addition, although this embodiment demonstrates what the three sensor parts of the 1st-3rd sensor parts 20-40 were daisy chain connected to ECU10, the several sensor part is further daisy chain connected to ECU10. Also good.

  First, the configuration of the first to third sensor units 20 to 40 will be described with reference to FIG. The first to third sensor units 20 to 40 have the same configuration, and the physical quantity detection units 21 to 41, the internal circuits 22 to 42, the current detection units 23 to 43, the transmission circuits 24 to 44, and the reception circuit 25, respectively. To 45 and control units 26 to 46.

  In the present embodiment, each of the physical quantity detection units 21 to 41 is an acceleration sensor that outputs a detection signal corresponding to the acceleration to the control units 26 to 46. Here, although each physical quantity detection part 21-41 demonstrates what is an acceleration sensor, each physical quantity detection part 21-41 may be an angular velocity sensor, a pressure sensor, etc.

  Each internal circuit 22-42 is a power supply circuit that generates a voltage for driving the physical quantity detection units 21-41, current detection units 23-43, transmission circuits 24-44, reception circuits 25-45, and control units 26-46. And various circuit elements. In the present embodiment, each of the internal circuits 22 to 41 is configured to be driven while consuming the current Icc generated by the ECU 10 when in the normal mode.

  Each of the current detection units 23 to 43 corresponds to the sensor unit current detection unit of the present invention, and a detection signal corresponding to the current flowing between the input side and the output side that is the ECU 10 side is sent to each control unit 26 to 46 is output. For example, when the first to third sensor units 20 to 40 are in the normal mode, currents Icc flow through the internal circuits 22 to 42, respectively. Therefore, the current detection unit 23 of the first sensor unit 20 detects the current 2Icc, and the current detection unit 33 of the second sensor unit 30 detects the current Icc. Further, in the current detection unit 43 of the third sensor unit 40, the sensor unit (internal circuit) is not disposed in the subsequent stage, and thus the current 0 is detected.

  Each transmission circuit 24 to 44 is connected to each control unit 26 to 46 and outputs a response current corresponding to the detection signal detected by the physical quantity detection unit 21 to 41 to the ECU 10 side. In this embodiment, the response current corresponds to the response signal of the present invention, and a pulsed current corresponding to each detection signal is output as the response current.

  Each of the receiving circuits 25 to 45 is connected to the control units 26 to 46, determines whether or not a wake-up signal (pulse voltage) is output from the ECU 10, and outputs a determination result to the control units 26 to 46. .

  Each of the control units 26 to 46 corresponds to a sensor unit control unit of the present invention, and is configured mainly with a microcomputer including a CPU, a ROM, a RAM, and the like. Then, for each predetermined period, it is determined whether to shift to a normal mode that consumes normal power, a sleep mode that consumes less power than the normal mode, or a response mode that shifts to the sleep mode after outputting a response current. .

  Specifically, each control unit 26 to 46 determines which mode is to be performed later based on the current detected by each current detection unit 23 to 43 and the mode at the time of determination. More specifically, when the detected current is less than the first threshold at the time of determination, each of the control units 26 to 46 follows the response mode when the current mode is the normal mode, and the current mode is When in the sleep mode, the sleep mode is maintained. Further, when the detected current is equal to or greater than the first threshold and less than the second threshold, the normal mode is entered. When the detected current is equal to or greater than the second threshold value, the sleep mode is entered.

  In the present embodiment, the first threshold value is Icc that is a current consumed by the first to third sensor units 20 to 40 (internal circuits 22 to 42), and the second threshold value is the first to third sensor units. 2Icc which is twice the current consumed by 20-40 (internal circuits 22-42). That is, when a current 0 that is less than the first threshold is detected, the response mode is followed when the current mode is the normal mode, and the sleep mode is maintained when the current mode is the sleep mode. Further, when a current Icc that is greater than or equal to the first threshold and less than the second threshold is detected, the normal mode is followed. When the current 2Icc that is equal to or greater than the second threshold is detected, the sleep mode is entered.

  Note that the mode transition includes, for example, a case where the current mode is the normal mode and the normal mode is maintained.

  The ECU 10 corresponds to the master device of the present invention, and includes a drive circuit 11, a current detection unit 12, and a control unit 13, as shown in FIG.

  The drive circuit 11 generates current consumed by the first to third sensor units 20 to 40 (internal circuits 22 to 42).

  The current detection unit 12 corresponds to the master device current detection unit of the present invention, and outputs a detection signal corresponding to the current flowing between the drive circuit 11 and the first sensor unit 20 to the control unit 13. That is, the current detection unit 12 detects the total current consumed by the first to third sensor units 20 to 40 (internal circuits 22 to 42) and is output from the first to third sensor units 20 to 40. The response current is detected.

  The control unit 13 corresponds to the master device control unit of the present invention, and is configured mainly with a microcomputer including a CPU, a ROM, a RAM, and the like. And various processes are performed based on the response current (detection result of the physical quantity detection units 21 to 41) output from the first to third sensor units 20 to 40. Further, when the current detected by the current detection unit 12 is less than the threshold (in this embodiment, the threshold is Icc and a current 0 that is less than the threshold is detected), the wake-up signal (pulse-like signal) Voltage) to output the first to third sensor units 20 to 40 to the normal mode.

  In addition, in this embodiment, although mentioned later concretely, after the 1st-3rd sensor parts 20-40 transfer to normal mode, the 3rd sensor part 40, the 2nd sensor part 30, the 1st sensor part 20 Response current is output in the order of. Therefore, the control unit 13 determines which one of the first to third sensor units 20 to 40 is the response current in the order in which the response current is input.

  The above is the configuration of the power communication apparatus in the present embodiment. Next, the operation of such a power communication apparatus will be described with reference to FIGS. 4 and 5. In FIG. 5, the receiving circuits 25 to 45 are omitted. In FIGS. 4 and 5, the normal mode is U-Mode, the sleep mode is S-mode, and the response mode is R-mode. Yes. Moreover, below, the case where an electric power communication apparatus is mounted in a vehicle is demonstrated. Furthermore, in the present embodiment, in the sleep mode, a minute current necessary for driving the physical quantity detection units 21 to 41 and the like is actually consumed by the internal circuits 22 to 42, but it is easy to understand. Therefore, the current consumed by each of the internal circuits 22 to 42 is set to zero.

  First, as shown in FIGS. 4 and 5A, when the vehicle is ignited at time T0, the ECU 10 (control unit 13) rises to the voltage Vc and the first to third sensor units 20 to 40 are activated. Subsequent to normal mode. That is, at time T0, the current Icc is consumed in the internal circuits 22 to 42 of the first to third sensor units 20 to 40. For this reason, the current detection unit 12 of the ECU 10 detects the current 3Icc. Further, the current detection unit 23 of the first sensor unit 20 detects the current 2Icc, the current detection unit 33 of the second sensor unit 30 detects the current Icc, and the current detection unit 43 of the third sensor unit 40 detects the current 0. Is detected.

  And the control parts 26-46 of the 1st-3rd sensor parts 20-40 are each current detection parts 23-43 for every predetermined period (this embodiment time T1, time T5, time T9, time T12). Whether to shift to the normal mode, the sleep mode, or the response mode is determined based on the current detected in step 1 and the mode at the time of determination.

  Specifically, as shown in FIG. 4 and FIG. 5B, the first sensor unit 20 goes into the sleep mode at the time T2 because the current detection unit 23 detects the current 2Icc at the time T1. For this reason, the current consumed by the internal circuit 22 at time T2 becomes zero.

  Further, the second sensor unit 30 maintains the normal mode after the time point T1, since the current Icc is detected by the current detection unit 33 at the time point T1.

  The third sensor unit 40 shifts to the response mode because the current detection unit 43 detects the current 0 at the time T1 and the mode at the time T1 is the normal mode. For this reason, after outputting the response current Ix3 based on the detection result detected by the physical quantity detection unit 41 via the transmission circuit 44 at time T3, the mode shifts to the sleep mode at time T4. Thereby, the current detection unit 12 measures the pulsed current value.

  As described above, the control unit 13 determines which of the first to third sensor units 20 to 40 is the response current in the order in which the response current is input. For this reason, since the response current Ix3 output at the time point T3 is the response current output first after the first to third sensor units 20 to 40 enter the normal mode, the control unit 13 at the time point T3. It is determined that the output response current Ix3 is a detection result detected by the physical quantity detection unit 41 of the third sensor unit 40.

  In addition, since the third sensor unit 40 goes into the sleep mode at time T4, the current 2Icc is detected by the current detection unit 12 after time T4.

  Next, as shown in FIGS. 4 and 5C, the first sensor unit 20 goes into the normal mode at time T6 because the current detection unit 23 detects the current Icc at time T5.

  The second sensor unit 30 shifts to the response mode at the time T7 because the current 0 is detected by the current detection unit 33 at the time T5 and the mode at the time T5 is the normal mode. For this reason, after outputting the response current Ix2 based on the detection result detected by the physical quantity detection unit 31 via the transmission circuit 34 at the time T7, the mode shifts to the sleep mode at the time T8. Thereby, the current detection unit 12 measures the pulsed current value.

  Since the response current Ix2 output at time T7 is the response current output second after the first to third sensor units 20 to 40 enter the normal mode, the control unit 13 receives the response current Ix2 at time T7. It is determined that the output response current Ix2 is a detection result detected by the physical quantity detection unit 31 of the second sensor unit 30.

  Further, since the second sensor unit 30 goes into the sleep mode after time T8, the current detection unit 12 detects the current Icc after time T8.

  The third sensor unit 40 maintains the sleep mode because the current detection unit 43 detects the current 0 at the time T5 and the mode at the time T5 is the sleep mode.

  Next, as shown in FIG. 4 and FIG. 5D, the first sensor unit 20 detects the current 0 at the time T9 at the time T9, and the mode at the time T9 is the normal mode. To switch to response mode. Then, after outputting the response current Ix1 based on the detection result detected by the physical quantity detection unit 21 via the transmission circuit 24 at time T10, the mode shifts to the sleep mode at time T11. Thereby, the current detection unit 12 measures the pulsed current value.

  In addition, since the response current Ix1 output at time T10 is the response current output third after the first to third sensor units 20 to 40 enter the normal mode, the control unit 13 receives the response current Ix1 at time T10. It is determined that the output response current Ix1 is a detection result detected by the physical quantity detection unit 21 of the first sensor unit 20.

  The second and third sensor units 30 and 40 maintain the sleep mode because the current detection units 33 and 43 detect the current 0 at the time T9 and the mode at the time T9 is the sleep mode.

  The first to third sensor units 20 to 40 maintain the sleep mode because the current detection unit to 2343 detects the current 0 at the time point T12 and the mode at the time point T12 is the sleep mode.

  Moreover, the control part 13 of ECU10 is detected by the electric current detection part 12 for every predetermined period (this embodiment time T1, time T5, time T12) similarly to the 1st-3rd sensor parts 20-40. It is determined whether the measured current is less than the threshold value. When the current detected by the current detection unit 12 is less than the threshold, a wakeup signal (voltage Vt) is output to shift the first to third sensor units 20 to 40 to the normal mode.

  Specifically, at the times T1, T5, and T9, the current detection unit 12 detects the current Icc or the current 2Icc, and at the time T12, the current 0 is detected. For this reason, at time T13, the control unit 13 outputs a wake-up signal (pulse voltage). Thereby, the wake-up signal is input to the first to third sensor units 20 to 40 via the receiving circuits 25 to 45, and at the time T14, the first to third sensor units 20 to 40 enter the normal mode, The operation after time T1 is performed again.

  As described above, in the present embodiment, the first to third sensor units 20 to 40 are shifted to the sleep mode with less current consumption after outputting the response current. For this reason, it is possible to reduce current consumption, and in turn reduce power consumption.

  The first threshold value is the current consumed by the first to third sensor units 20 to 40 (internal circuits 22 to 42). For this reason, the response current is output in the order of the third sensor unit 40, the second sensor unit 30, and the first sensor unit 20. Therefore, the ECU 10 can determine from which sensor unit the response current is output by grasping the order in which the response current is input.

  Furthermore, in the present embodiment, when a current (current 2Icc) equal to or greater than the second threshold is detected, the mode is shifted to the sleep mode. For this reason, current consumption can be further reduced.

(Other embodiments)
The present invention is not limited to the embodiment described above, and can be appropriately changed within the scope described in the claims.

  For example, in the first embodiment, when the current 2Icc is detected by the current detection unit 23 at the time T1, the normal mode may be maintained. Even in such a power communication device, since the first to third sensor units 20 to 40 shift to the sleep mode after outputting the response current, it is possible to reduce current consumption.

  Moreover, in the said 1st Embodiment, although the control part 13 of ECU10 and the control parts 26-46 of the 1st-3rd sensor parts 20-40 determined at the same time, the control part 13 of ECU10 and The control units 26 to 46 of the first to third sensor units 20 to 40 may make determinations at different times.

  Furthermore, in the first embodiment described above, the first sensor unit 20 shifts to the sleep mode at the time T2, and the third sensor unit 40 outputs the response current at the time T3. However, the time when the first sensor unit 20 shifts to the sleep mode and the time when the third sensor unit 40 outputs the response current may be the same time. Similarly, the time when the first sensor unit 20 enters the normal mode and the time when the second sensor unit 30 outputs the response current may be the same time. That is, the transition point after the determination can be changed as appropriate.

10 ECU (master device)
20 to 40 First to third sensor units 21 to 41 Physical quantity detection unit 23 to 43 Current detection unit 26 to 46 Control unit

Claims (4)

A master device (10) that performs predetermined processing based on a physical quantity;
A plurality of sensor units (20-40) having a physical quantity detection unit (21-41) for detecting the physical quantity and daisy chain connected to the master device;
The master device (10) includes a master device current detection unit (12) that detects a total current consumed by the plurality of sensor units,
The plurality of sensor units have the same configuration, and together with the physical quantity detection unit, a sensor unit current detection that detects a current flowing between the input side which is the master device side and the output side opposite to the input side. Unit (23-43) and a normal mode that consumes a normal current, or after outputting a response signal based on the detection result detected by the physical quantity detection unit, transition to a sleep mode that consumes less current than the normal mode It has a sensor part control part (26-46) which judges whether it changes to any of response modes,
Each of the sensor unit control units in the plurality of sensor units shifts to the response mode when the current detected by the current detection unit is less than a first threshold and the mode at the time of determination is a normal mode,
The master device outputs the wake-up signal when the current flowing through the master device current detection unit becomes less than a predetermined threshold due to the plurality of sensor units entering the sleep mode, thereby outputting the plurality of sensor units. Is shifted to the normal mode.   The power communication apparatus according to claim 1, wherein the first threshold value is equal to a current consumed by one of the sensor units.   When the detection result detected by each of the current detection units is equal to or greater than a second threshold value that is greater than the first threshold value, each of the sensor unit control units in the plurality of sensor units follows the sleep mode, and The normal mode is followed when the detection result detected by the current detection unit after the sleep mode is equal to or greater than the first threshold and less than the second threshold. 2. The power communication apparatus according to 2. The power communication apparatus according to claim 3, wherein the second threshold value is equal to twice the current consumed by one of the sensor units.

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